Slides Week 3 Flashcards
Cognitive Developments
- Dramatic shifts in thinking, knowing, and remembering occur over the first ten years of life.
- These shifts in contribute to psychosocial developments in adolescence and adulthood
- e.g., the formation of identity
- Cognitive developmentalists attempt to explain the mechanisms underlying these shifts.
4 Approaches to Cognitive Development
- Neurobiological
- Developmental (Piaget 1952)
- Psychometric Intelligence Tests
- Information Processing
Neurobiological Approaches
Growth of the brain and its effect on development
Cells in the Nervous System
- The nervous system is living tissue composed of cells
- The firing of billions of nerve cells provides the physiological basis for psychological processes
- Two major categories of cells in the nervous system
- Glia
- Neurons
Glia
- A supportive cell in the central nervous system.
- Glial cells do not conduct electrical impulses like neurons
- Glial cells surround neurons and provide support for and insulation between them.
- Most abundant cell types in the central nervous system.
Neurons
- Specialized cells that transmit chemical and electrical signals in the brain
- Basic building blocks of the central nervous system.
- As we develop (over time):
- No of dendrites increases
- More connections
- Myelin sheath increases
- Length of axon increases
- No of dendrites increases
Cerebrum: Four Lobes
- Frontal
- Parietal
- Occipital
- Temporal
Brain Develops at Different Stages
- Frontal lobe
- Executive functions: planning, inhibitory control, intention, personality
- Develops later (compared to other stages) = Poor decision making earlier (esp in adolescence!)
- Parietal lobe
- Spatial information, attention, motor control
- Occipital lobe
- -Vision
- Temporal lobe
- Memory (short term/long term), hearing, language processes
- Cerebellum
- Receives information, balance, coordination, speech (muscle control)
- Brain stem
- Important life functions (breathing, swallowing, heart rate, blood pressure), flow of information between brain and body
Two techniques to study Neural Changes
- Positron Emission Tomography (PET).
- Functional Magnetic resonance Imagery (fMRI).
Positron Emission Tomography (PET).
- Radioactive traces introduced to bloodstream
- Produces 3-D image of functional processes in the body.
- Identify which parts of brain activated during activities across differing subjects
Kalat (2016) - Positron Emission Tomography
Positron-emission tomography (PET) provides a high-resolution image of activity in a living brain by recording the emission of radioactivity from injected chemicals. First, the person receives an injection of glucose or some other chemical containing radioactive atoms. Glucose use increases in the most active brain areas, so tracking the levels of glucose tells us something about brain activity. When a radioactive atom decays, it releases a positron that immediately collides with a nearby electron, emitting two gamma rays in exactly opposite directions. The person’s head is surrounded by a set of gamma ray detectors (see Figure 3.32). When two detectors record gamma rays at the same time, they identify a spot halfway between those detectors as the point of origin of the gamma rays. A computer uses this information to determine how many gamma rays came from each spot in the brain and therefore how much of the radioactive chemical is located in each area (Phelps & Mazziotta, 1985). The areas with the most radioactivity are presumably the ones with the most active neurons.”
Functional Magnetic Resonance Imaging
- fMRI detects neural activity in brain by detecting associated changes in blood flow related to changes in energy used by brain cells.
- “Hemoglobin with oxygen reacts to a magnetic field differently from hemoglobin without oxygen. Researchers set the fMRI scanner to detect the amount of hemoglobin with oxygen (Viswanathan & Freeman, 2007). When a brain area becomes more active, two relevant changes occur: First, blood vessels dilate to al- low more blood flow to the area. Second, as the brain area uses oxygen, the percentage of hemoglobin with oxygen de- creases. An fMRI scan responds to both of these processes (Sirotin, Hillman, Bordier, & Das, 2009).
Neural Development over the Lifespan
- Advances in technology have shown:
- Particular neural changes associated with each stage of the lifespan.
- These changes are potentially related to the cognitive abilities that develop in each stage.
- Infancy:
- Brain growth.
- Childhood:
- Lateralisation.
- Plasticity.
- Adolescence:
- Cortical changes.
- Adulthood:
- Gain-loss dialectic.
Neural Development in Infancy
- Rapic Growth of the Brain
- Neurocognitive Growth
- Not just brain size but neuron density
Brain Weight
- Birth - 25% adult weight
- 2 Years - 80% adult weight
- This rapid neurocognitive growth spurt during infancy is differentially distributed across different areas, structures, and functioning of the brain.
- FOUR factors important in increase in brain weight in infancy:
- Neurons
- Dendrites.
- Synapses.
- Myelination
Brain at Birth
- Subcortical structures are most mature.
- Cerebral cortex most immature, particularly frontal areas.
- Mechanisms of voluntary self-control and deliberate self-regulation of reflex responses are rare in children < 4 years old.
- Infants have their full quota of brain cells, but the neural connections between these cells are not developed
- As the infant matures, connections become more complex and more efficient.
Dendrites + Synapses + Cortex
- Specifically, rapid growth in dendrites and synaptic connections among brain cells combines with cortical maturation
- Resultant behaviours:
- Capacity to control neck muscles
- Motor co-ordination for sitting upright.
- Gains in socialisation.
Cortex Take Over
- Cortex takes over voluntary control from lower brain centre
- Changes occur in reflexes, attention and sleep patterns
Positive Babinski Effect
- Is normal in infants until around 12 - 24 months
- In adults indicates possible damage to the cortico-spinal tract
Dendrites
- Addition of dendrites and axon terminals to form interconnections with each other.
-
Transient exuberance:
- Initial dramatic burst of growth of dendrites.
- Allows brain to organise itself in response to stimulation from outside world.
Transient Exuberance
- Dendrite growth
- Large but temporary increase in the number of dendrites that develop in infant’s brain
- Occurs during the first two years of life. …
- Enables neurons to connect and communicate by greatly expanding number of other neurons within the brain.
Synapses
- Growth of Synapses followed by pruning to simplify brain’s wiring
- Streamlines brain activity with maximum efficiency
Myelination
- Process of myelination:
- Speeds transmission of neural impulses.
- Rapid information processing.
- Brain gains control over motor functioning.
- Myelination of neuron channels, pathways and modular interconnections (up until 10 years).
- Process of myelination governed by glial cells (which continue to grow throughout life, unlike neurons).
Two Significant developments of the Cerebral Cortex
- Limbic System (Medial temporal lobe)
- Frontal lobe.
Limbic System
- In the medial temporal lobe
- Loosely connected network that contributes to emotion, memory, and motivation
- Includes:
- Amygdala
- Hippocampus
- 6 months – 12 months:
- Remember and imitate actions.
- Recognize picture of object held in hands.
*
Frontal Lobe
- Develops in Later Childhood
- Higher Cognitive functions like reasonig
Laterilisation
- Functional dominance of one hemisphere over the other
- One hemisphere is more responsible or entirely responsible for control of a function in comparison to the other.
Brain Growth in Childhood
- Continues during childhood
- Primary neural developments associated with this stage are:
- Increase in brain size and volume.
- Myelination.
- Lateralisation.
Plasticity
- Brain’s potential for growth and flexibility to change in response to experience.
- Increase in brain size and volume, Myelination and Lateralisation contribute to brain’s plasticity
Childhood Increase in Brain Size
- 90% of adult volume by age 5.
- Giedd (2003) - MRI of brains of 1500 healthy children.
- Growth in brain’s grey matter à arborisation.
- Only most efficient and functional brain connections remain in human brain.
- Enhances plasticity in response to early experience.
Myelinatation
- Myelination follows sequence in childhood:
- Sensory pathways at birth.
- Hippocampus at 6 years (accounts for improved memorisation ability in preschool).
- Reticular formation (brainstem; alertness and arousal) + frontal cortex process completes in adolescence.
Laterlisation in Childhood
- In childhood, the cerebral cortex becomes specialised for particular functions.
- Hemispheres connected by corpus callosum.
- Continued growth and myelination in childhood.
- Specialisation for handedness and language begins in preschool and ends at puberty.
- Sensitive (or critical) period for language development.
- Implications for second language learning
Corpus Callosum
Neural Development in Adolescence
- Emphasis on prefrontal cortex
- Cognitive abilities are significantly more developed than in childhood:
- Astract (cf. concrete à possible cf. real)
- Metacognitive
- Multidimensional (cf. unidimensional).
- Relativistic (cf. absolute).
Adolescent Behaviour, Emotion & Cognition
- THREE aspects of brain maturation linked with behvioural, emotional, and cognitive development during adolescence:
- Cortical synapses.
- Neurotransmitters in limbic system.
- Synaptic pruning and myelination of the prefrontal cortex.
Cortical Synapses
- Growth means more efficient and focused information processing
Neurotransmitters
- Changes to neurotransmitters in limbic system:
- More emotionality.
- More responsive to stress.
- Less responsive to rewards